Aircraft

ABSTRACT

In an aircraft wing flap extending and retracting assembly, the flap is carried from a pivotal mounting on a downward extension of a main bogie that runs in a main track fixed to the trailing portion of the wing, and is additionally supported, at a position displaced in the fore-and-aft direction from the main pivot, by a support member that depends from a further pivot on the main bogie and carries a runner travelling along a incidence control track. Both the main and incidence control tracks are above the recess in which the flap is housed when retracted, and above the path followed by the flap when it extends, so that the flap is not interrupted to allow passage of either track. A tab pivoted on the flap is operated by a linkage connection to the main bogie.

United States Patent Bonney 1 AIRCRAFT [72] Inventor: Kenneth Victor Bonney, Welwyn Garden City, England [73] Assignee: Hawker Siddeley Aviation Limited,

Surrey, England [22] Filed: Jan.1l,1971

[21] Appl. No.1 105,522

[30] Foreign Application Priority Data Jan. 12, 1970 Great Britain ..1,476/70 [52] U.S. Cl f. ..244/4-2 DA [51] Int. Cl ..B64c 3/50 [58] Field of Search ..244/42 DA, 42 DB, 42 CB, 244/42 R, 43

[56] References Cited UNITED STATES PATENTS 2,836,380 5/1958 Pearson ..244/42 DB 3,528,632 9/1970 Miles et a1 ..244/42 DA 1 Oct. 17,1972

2,661,166 12/1953 Gordon ..244/42 DB Attorney-Dowell & Dowell [57] ABSTRACT In an aircraft wing flap extending and retracting assembly, the flap is carried from a pivotal mounting on a downward extension of a main bogie that runs in a main track fixed to the trailing portion of the wing, and is additionally supported, at a position displaced in the fore-and-aft direction from the main pivot, by a support member that depends from a further pivot on the main bogie and carries a runner travelling along a incidence control track. Both the main and incidence control tracks are above the recess in which the flap is housed when retracted, and above the path followed by the flap when it extends, so that the flap is not interrupted to allow passage of either track. A tab pivoted on the flap is operated by a linkage connection to the main bogie.

10 Claims, 13 Drawing Figures SHEET 2 BF 7' PATENTEDHBI 11 1912 Mama: 7

Home

PATENIEDnm 11 1912 SHEET Q [If 7 PATENTEDHBI 1 1 I912 3. 6 98 664 SHEET 5 OF 7 9 I L'j I Latin PATENTEDHBT 17 I972 SHEET 8 OF 7 A Home AIRCRAFT This invention relates to aircraft wing flaps and more particularly to means for operating wing flaps to ensure the widest range of rearward extension accompanied by varying amounts of flap deflection relative to the wing section datum.

Wing flaps are employed primarily to reduce the stalling speed of an aircraft of a given weight or to reduce the aerodynamic loading on the lifting surfaces in a given set of conditions, by two main effects:

a. by translating the flap rearwards relative to the wing, thereby increasing the effective wing area.

b. by deflection downwards, thereby increasing the wing camber and flow circulation.

Criteria essential to the proper aerodynamic behavior of the complete system, are the shapes of the flap, the wing rear shroud and the airflow slot which is formed as the flap separates from therear shroud during the rearward translation and final stages of deflection. It is an object of the invention to provide an improved flap control arrangement whereby no substantial change in flap incidence occurs until, say, the last 30 percent of rearward movement is reached. It is a further object to ensure that the airflow slot is convergent to the point at which the air is expelled over the flap upper surface,'throughout the whole range of flap movement.

According to the present invention, the flap is supported in its' rearward travel by being pivotally mounted on a bogie or support running along a main track or guide on the wing structure, and separate incidence control of the flap is obtained by turning of the flap about its pivotal mounting on the bogie by means of a second connection to an incidence control member which runs in a separate incidence control track or enters an incidence control extension of the main running track, the track or tracks being disposed substantially wholly above the path of the flap.

The flap may be formed as two aerofoil elements, the rearmost element being hinged on the main flap to provide a tab action. By interposing a linkage to the primary control drive, this tab is caused to deflect relatively to the main flap, increasing the effective camber of the lifting system, and causing a variation in the lift and drag for effect during the landing approach and touchdown phases.

In one embodiment, two tracks are disposed one above the other,-one carrying a travelling bogie which supports the flap at a point near to its mid-chord while the other track is employed for control of the flap attitude (incidence) by means of a rocking lever attached to the leading edge region of the flap. In another embodiment, two tracks are again provided one above the other. One track carries a travelling bogie which supports the flap at a point near its leading edge, while the other track is employed for control of the flap attitude (incidence) by means of a link attached to the flap at a point further aft. Alternatively, there may be only a single track with varying curvature, carrying a bogie on which the flap is mounted near to its leading edge, whilst a rocking lever on the bogie is employed for incidence control, this lever also engaging the track at a position spaced along it from the bogie.

Various arrangements in accordance with the invention will now be described by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a half plan of an aircraft wing with a flap which can be extended and retracted by means according to the present invention,

FIG. 2 shows one of the flap-extending and retracting mechanisms in elevation, with the flap in the retracted position,

, FIG. 3 shows the mechanism of FIG. 2 with the flap at an intermediate stage in its extension,

FIG. 4 shows the mechanism of FIG. 2 with the flap fully extended,

FIGS. 5 to 7 show a second embodiment in three views corresponding to FIGS. 2 to 4,

FIGS. 8 to 10 show a third embodiment in three views corresponding to FIGS. 2 to 4, and

FIGS. 11 to 13 show a fourth embodiment in three views corresponding to FIGS. 2 to 4.

FIGS. 1 to 4 show an adaption of a known circulararc track system. This known system, if used without the modification now proposed, produces a flap motion which has the following undesirable characteristics;

a. Rearward translation of the flap produces a rapid increase in flap incidence for only a small increase in wing area.

b. Over the major portion of the total translation, the airflow slot which opens up between the wing rear shroud and the flap upper surface is very small an divergent instead of convergent.

These disadvantages are overcome in the system shown by providing a flap incidence control mechanism which functions as now described.

As shown in plan in FIG. 1, the wing 8 of an aircraft has a flap l3 operated by two flap-extending and retracting units 10 spaced along the wingQOne of these flap-extending and retracting units is shown in elevation in FIGS. 2m 4. FIG. 2 illustrates the stowed or retracted position of the flap in which it is received in a recess 34 in the under side of the trailing portion 8A of the fixed wing.

In each unit 10 a bogie 11 is driven by any convenient means along a circular-arc track 12. The flap 13 (or the main section of the flap if a tab 14 is included as shown) is pivoted, at its approximate lift center, on a rearward extension of the'bogie 11 at a point 15 some distance below the track 12. The nose of the flap 13 is connected by a link 16 to the lower end of a depending arm of a rocking lever 17 also pivoted on the bogie 11 at a point 18 fairly well forward on the bogie and above the track 12. The lever 17 is controlled by an additional incidence-control track 19 which is above the track 12 and in which runs a roller 20 on the rear end of an arm of the lever 17 that extends rearwardly from the pivot point 18. As the bogie ll translates rearwards the rocking lever 17 pushes the nose of the flap l3 downwards from the normal circular-arc path thus maintaining a low incidence. This vergent airflow slots of the required size and it is possible to arrange the two tracks 12 and 19 so that any desired combination of slot configuration and. flap incidence can be achieved.

The hinged tab feature included in the system shown is provided to reduce the maximum incidence required on the main flap for the aircraft approach and landing conditions. It comes into operation shortly after the main flap has reached the point of maximum deviation from the normal circular-arc motion as shown in FIG. 3.

The tab 14 has a web 22 extending below it and pivots about a hinge 23 located at the bottom forward region of the web 22 and connecting this web to an arm 24 projecting rearwardly and downwardly from the main flap 13. The'tab is deflected with respect to the main flap by two fore-and-aft extending pivoted links 29 pushed rearwards by a lever 25 that is in turn controlled by a reverse-curved rearward extension 26 of the main track 12. The lever 25 has a pivot 27 on the bogie 11, a roller 7 running in the main track 12 immediately behind the bogie 11, and an arm 28 depending from the pivot 27 with its lower end pivotally connected to the forward end of one of the links 29. This link extends rearward for pivotal connection to the forward end of the second link which in turn has its rear end pivotally connected to the nose of the tab 14 at 30. The point of articulation 31 of the two links 29 is'connected by a short downwardly-extending link 32 to a pivot point 33 provided at the lower end of a portion of the main bogie 11 projecting down below the pivot 15. As the tab 14 deflects a convergent slot is opened up between the tab 14 and flap 13 thus increasing the airflow circulation around both.

A similar mechanism could be used to operate a simple plain-hinged tab instead of the slotted variety. It will be observed that both tracks 12 and 19 lie entirely above the path of the flap and tab which therefore do not have to be cut in any way to allow passage of these tracks. The portions of the flap-extending and retracting mechanism 10 that project above the trailing portion 8A of the fixed wing are enclosed in a shroud or fairing 37.

FIGS. to 7 of the drawings show an adaption of a known hockey stick track system which, without the modification now proposed, involves cutting through the flap at each track unit with a consequent increase in weight and reduction in flap efficiency. In the system now described this disadvantage is overcome by running the normal articulated bogie on two tracks both of which are above the line of flap movement, which allows the flap to be kept in one piece and gives a cleaner airflow over the flap.

The forward part 54 of the articulated bogie is driven in any appropriate manner along a generally straight lower track 35 whilst the pivoting rear portion 36 projects upward to be guided by the hockey stick type upper track 38. The flap 13 (or main flap if a tab 14 is included as shown) is hinged near its leading edge at the bogie articulation point 39 which is disposed below the lower track 35. The flap 13 is also supported further aft by a link or links 40 depending from the rear portion 36 of the bogie. As the flap translates rearwards the incidence is controlled by the upper track 38 independently of the lower track 35 which is used to control the size of the airflow slot 41 between the wing trailing portion 8A and the flap upper surface. It is possible, therefore, to arrange the two tracks 35, 38 so that any desired combination of convergent airflow slot and flap below the trailing portion of the main flap 13 and is connected by a long fore-and-aft link-42 to an anchor point 43 on a portion of the forward part 54 of the bogie that depends below the main pivot 39. The point 43 is positioned relative to the main bogie pivot 39 such that deflection of the flap 13 automatically produces the required rearward movement and deflection of the tab 14 and opens up a convergent slot 41 between the tab and the flap.

Again, a similar mechanism could be used to operate a simpie plain-hinged tab; and both tracks 35, 38 lie wholly above the path of the flap.

FIGS. 8 to 10 show a simplification of the system of FIGS. 5 to 7, for use with a constant chord flap with the track units 10 arranged in a plane at right angles to the flap hinge line. The system functions in the same manner as before except that the rear bogie part 36 is now fastened directly to the flap 13, instead of being pivoted to the forward bogie part 54 and connected to the flap by a link or links. This reduces the number of moving parts with a consequent reduction in cost, complication and weight.

FIGS. 11 to 13 show a further adaption of the basic circular-arc'track system which overcomes the disadvantages of the latter with a single track arrangement, as distinct-from the arrangement of FIGS. 2 to 4 which has two tracks. This reduces the depth of the track unit fairing 37 required, with a consequent reduction in drag.

A bogie 44 is driven in any appropriate manner along a large radius circular-arc track 45. The radius and setting of this track 45 is determined by the flap incidence and position required for the aircraft take-off condition, rather than by the aircraft landing condition as in the arrangement of FlGS. 2 to 4. The flap 13 (or main flap if a tab 14 is included as shown) is hinged at a low pivot point 46 near its leading edge on a depending portion of the bogie 44 below the track 45, and is supported further aft by a link or links 47 connected to a forwardly and downwardly extending arm of a rocking lever 48 pivoted at 49 on the rear end of the bogie 44. The lever 48 itself has a portion running like a bogie in the track 45 aft of the bogie 44 and is used to control the incidence of the main flap 13 after the datum takeoff position (FIG. 12) is reached. For this purpose, a more sharply and reverse curved rearward extension 50 of the circular-arc track 45 is provided such that further translation of the bogie 44 past the datum takeoff position causes the lever 48 to enter this reverse curved portion 50 of the track and rotate, pushing the link(s) 47 downwards with consequent deflection of the flap 13 to the desired setting. At all times during the translation of the flap the resulting airflow slot 41 between the wing rear shroud and the flap upper surface is convergent.

The hinged tab 14 comes into operation immediately the flap l3 translates past the datum take-off position. The tab 14 pivots about the hinge 23 provided low at the rear of the main flap l3 and is pushed rearwards and deflected by a fore-and-aft extending link 51, connected at its forward end to the link 47, during the last portion of the travel of the flap, Thus, a convergent slot is opened up between the tab and flap, increasing the airflow circulation around both. A similar mechanism could be used to operate a simple plain hinged tab, as

before.

A further feature of this system is that a lift-dumping drag-increasing flap/tab position can easily be provided, if required, to reduce the aircraft landing run. This is achieved by adding a small further rearward and upward extension 52 to the incidence control portion 50 of the track 45. A small final movement of the bogie 44 then produces a small decrease in main flap incidence and a large increase in tab deflection and slot width. The effect of this is a reduction in lift/drag ratio due mostly to the tab 14 being stalled.

As before, the track lies entirely above the path of the flap.

What I claim is:

1. An aircraft wing flap assembly, comprising a wing with a trailing portion having a recess in its underside shaped to receive a movable wing flap when the flap is retracted, a wing flap occupying a position in said recess when retracted, means for translating said flap between said retracted position and an extended position substantially aft of said wing trailing portion, a flap support track fixed to said wing trailing portion and extending generally fore and aft above said recess so that the flap when retracted is substantially wholly at a level below said flap support track, a bogie mounted to travel along said flap support track, flap suspension means pivotally suspending said flap from said bogie, flap incidence control track means fixed to said wing trailing portion and extending aft of said flap when the flap is retracted but lying above the path taken by the flap as it translates between its retracted and extended positions, and an incidence control runner which travels along said incidence control track means as said flap translates and has a connection to said flap whereby said flap is turned about its suspension pivot on said flap suspension means during translation of the flap thereby to change the flap incidence.

2. An assembly according to claim 1, wherein the flap comprises a main flap section and a separable and relatively deflectable tab section, the tab being operated automatically as the flap is extended by a linkage interconnecting the tab and the bogie.

3. An assembly according to claim 2, wherein two tracks are fixed to the trailing portion of the wing one above the other, so that they extend generally fore-andaft over said recess in the underside of the wing trailing portion in which the flap is received when retracted, the lower track guiding the bogie while the upper track constitutes the incidence control track means.

4. An assembly according to claim 3, wherein the flap is pivotally mounted, in the region of its center of lift, on a rearward and downward extension of the b0 ie, and is additi nall su orted at its nose b a cor mection to a rocking le ver Fli at depends from a pii 'ot on the bogie and has a portion carrying said runner that travels along the incidence control track.

5. An assembly according to claim 4, wherein the bogie track is substantially part-circular and the incidence control track is cranked and has a portion gradually rising in the rearward direction followed by a more sharply descending after portion.

6. An assembly according to claim 4, wherein the tab-operating linkage is connected to a second rocking lever that depends from a pivot on the bogie and has a portion carrying a-second runner that travels along the bogie track aft of the bogie.

7. An assembly according to claim 3, wherein the flap is pivotally mounted, in the region of its nose, on a downward extension of the bogie, and is additionally supported further aft by a further bogie section carrying said runner travelling along the incidence control track.

8. An assembly according to claim 7, wherein said further bogie section is articulated to the main bogie, and the flap is supported by it through the intermediary of a swinging depending link.

9. An assembly according to claim 7, wherein the bogie track is substantially straight and the incidence control track is of the hockey stick" type.

10. An assembly according to claim 2, wherein the flap is pivotally mounted, in the region of its nose, on a downward extension of the bogie and is additionally supported further aft by a swinging link pivotally connected to a rocking lever that extends down from a pivot on the bogie and has a portion carrying said runner that travels in the bogie track aft of the bogie,

the track being primarily part-circular but having a rearward upturned extension constituting said incidence control track means.

11. An assembly according to claim 10, wherein the tab-operating linkage includes the swinging link.

12. An assembly according to claim 10, wherein the bogie track has an additional extreme aft end portion of its upturned extension that serves to bring about lift dumping and increased drag by deflection and separation of the tab to an extent such that the tab enters a stalled condition. 

1. An aircrafT wing flap assembly, comprising a wing with a trailing portion having a recess in its underside shaped to receive a movable wing flap when the flap is retracted, a wing flap occupying a position in said recess when retracted, means for translating said flap between said retracted position and an extended position substantially aft of said wing trailing portion, a flap support track fixed to said wing trailing portion and extending generally fore and aft above said recess so that the flap when retracted is substantially wholly at a level below said flap support track, a bogie mounted to travel along said flap support track, flap suspension means pivotally suspending said flap from said bogie, flap incidence control track means fixed to said wing trailing portion and extending aft of said flap when the flap is retracted but lying above the path taken by the flap as it translates between its retracted and extended positions, and an incidence control runner which travels along said incidence control track means as said flap translates and has a connection to said flap whereby said flap is turned about its suspension pivot on said flap suspension means during translation of the flap thereby to change the flap incidence.
 2. An assembly according to claim 1, wherein the flap comprises a main flap section and a separable and relatively deflectable tab section, the tab being operated automatically as the flap is extended by a linkage interconnecting the tab and the bogie.
 3. An assembly according to claim 2, wherein two tracks are fixed to the trailing portion of the wing one above the other, so that they extend generally fore-and-aft over said recess in the underside of the wing trailing portion in which the flap is received when retracted, the lower track guiding the bogie while the upper track constitutes the incidence control track means.
 4. An assembly according to claim 3, wherein the flap is pivotally mounted, in the region of its center of lift, on a rearward and downward extension of the bogie, and is additionally supported at its nose by a connection to a rocking lever that depends from a pivot on the bogie and has a portion carrying said runner that travels along the incidence control track.
 5. An assembly according to claim 4, wherein the bogie track is substantially part-circular and the incidence control track is cranked and has a portion gradually rising in the rearward direction followed by a more sharply descending after portion.
 6. An assembly according to claim 4, wherein the tab-operating linkage is connected to a second rocking lever that depends from a pivot on the bogie and has a portion carrying a second runner that travels along the bogie track aft of the bogie.
 7. An assembly according to claim 3, wherein the flap is pivotally mounted, in the region of its nose, on a downward extension of the bogie, and is additionally supported further aft by a further bogie section carrying said runner travelling along the incidence control track.
 8. An assembly according to claim 7, wherein said further bogie section is articulated to the main bogie, and the flap is supported by it through the intermediary of a swinging depending link.
 9. An assembly according to claim 7, wherein the bogie track is substantially straight and the incidence control track is of the ''''hockey stick'''' type.
 10. An assembly according to claim 2, wherein the flap is pivotally mounted, in the region of its nose, on a downward extension of the bogie and is additionally supported further aft by a swinging link pivotally connected to a rocking lever that extends down from a pivot on the bogie and has a portion carrying said runner that travels in the bogie track aft of the bogie, the track being primarily part-circular but having a rearward upturned extension constituting said incidence control track means.
 11. An assembly according to claim 10, wherein the tab-operating linkage includes the swinging link.
 12. An assembly according to claim 10, wherein the bogie track has an additional extreme aft end portion of its upturned extension that serves to bring about lift dumping and increased drag by deflection and separation of the tab to an extent such that the tab enters a ''''stalled'''' condition. 